The precise locating of a target is essential during surgical procedure to reduce the morbidity rate. During the course of a surgical procedure shift deformation of organic tissues may occur. For example, during surgical procedure for ablation of a brain tumour, this deformation may occur after an opening has been made in the patient's skull. Such deformation may be related to physical phenomena (gravity, loss of cerebrospinal fluid, neurosurgeon manoeuvres, etc.) or to physiological phenomena (tumefaction due to osmotic drugs, anaesthetics, etc.) of which some are currently unknown.
To compensate for this shifting of organic tissues and to retrieve the pre-operative data of the patient during the surgical procedure, shift compensation for organic tissue deformation can be achieved on the following principle. A first image of a region of the organic tissues is acquired before the surgical operation. During the surgical operation, a second image of the same region is acquired. System processing means process these two images to align the points in the two images to offset the shifting of organic tissues. To align the points in the two images, the processing means use an image registration method. However, registration methods do not allow the points in two images to be exactly aligned when the characteristics of the data given in the two images are heterogeneous.
It is one objective of the present invention to propose a method for registering a set of source points in a first image with a set of target points in a second image, the set of source points being of different type to the set of target points due to the difference between overlapping data regions or to the presence of noise.